辽河断陷西部凹陷古近系砂岩储层

SANDSTONE RESERVOIRS CHARACTRISTICS OF THE PALEOGENE IN WESTERN DEPRESSION OF LIAOHE RIFT

辽河断陷西部凹陷是一个典型的箕状凹陷。受节节下掉正断层的控制 ,区内在古近系发育了陡坡型和缓坡型两种沉积模式。经过初陷—裂陷、扩张和再陷三个构造—沉积演化期 ,区内沉积了以源近流短的扇三角洲、湖底扇等为主的粗碎屑砂岩储层。该储层经历压实、胶结和溶蚀等过程 ,目前主要处于早成岩阶段和晚成岩A期。在沉积和成岩双重控制之下 ,砂岩储层的孔隙类型以粒间扩大孔隙为主。压实作用损失的孔隙大于胶结作用损失的孔隙。储层在纵向上发育有多个次生孔隙发育带。古近系砂岩储层物性和含油性都以扇三角洲砂岩储层最好 ,是该凹陷最重要的油气储层。研究认为该区深层具有很大的油气勘探潜力。

The Western Depression of Liaohe Rift is a typical half-graben depression. Controlled by step normal faults, two kinds of sedimentation models developed here, gentle and steep slope during the Paleogene. After experiencing three stages of structure-sedimentation evolution, its are, namely, initial subsidence-rifting depression, spreading and redepression, which are characterized by proximal provenance and short transportation sistance. Coarse clastic fan-delta, lacustrine fan sandstone reservoirs are developed. Having undergone compaction, cementation and dissolution processes, the reservoirs are mainly in early diagenesis stage and late diagenesis stage A. Doublly controlled by sedimentation and diagenesis, the main pore types of the sandstone reservoirs are intergranular overgrowth pore. The pore losing by compaction is larger than that by cementation. Several secondary porosity development zones are developed in the sandstone reservoirs vertically. Based on the sandstone reservoir quality and petroliferous property, the fan-delta reservoirs are the best compared to the other reservoirs, and they are the most important hydrocarbon reservoirs in this Depression. This research indicates that deep exploration has great hydrocarbon potential. The oil and gas exploration directions are pointed out also.